A rollover protection system (ROPS) of a machine, such as an articulated wheel loader, provides protection for an operator of the machine in the event of a rollover. The ROPS generally includes a two-post or four-post frame, or cab that is secured to the frame of the machine. If the machine is rolled over, resulting in a lateral force being applied to the ROPS, it is important for the force or load to be transferred from the ROPS to the frame of the machine. A robust connection must, therefore, exist between the ROPS and the frame in order to successfully transfer such a load.
In conventional assemblies, one or more support plates for mounting the ROPS are welded directly to a portion of the frame. These welded joints are subject to extreme stress, not just in the event of a rollover, but also during normal operation of the machine. As large loads are applied to the machine frame, any deflection or bending of the frame structure tends to occur at the joint connecting the ROPS plates to the frame. Extreme and/or cyclic stresses on these joints may ultimately lead to the development of fatigue cracks and possibly failure of these welds.
In an articulated machine, the ROPS plates are typically mounted to a rear frame assembly of the machine. The rear frame assembly supports an engine of the machine and is pivotally connected at an articulation joint to a front frame assembly. The front frame assembly is articulated with respect to the rear frame assembly by a pair of steering cylinders that are continually extended and retracted during a normal duty cycle of the machine. The large steering forces affecting each of the frame assemblies due to this continual movement result in repetitive flexing of the rear frame assembly with respect to the ROPS support plates mounted thereon. These cyclic stresses, concentrated at the joint connecting the rear frame assembly and the ROPS plates, may reduce the fatigue life and ultimately lead to failure of the welded joint.
To account for this, methods have been introduced to improve the strength and durability of such a welded joint. For example, U.S. Pat. No. 4,134,507 teaches annular fillet welds that connect a bracket to a flexing beam assembly. Specifically, the bracket includes first and second ends. The first end includes a round opening having a welded joint extending substantially around the periphery of the opening to connect the bracket to a lift arm of a loading vehicle. The second end of the bracket includes a load bearing connecting joint for pivotally connecting the bracket to the vehicle. The annular fillet welds are located along a low stress area of the lift arm and provide a means for transferring loads or forces to the low stress area. This reference does not, however contemplate concentrating or consuming the load within an intermediary piece that connects the bracket to the flexing beam assembly.
The present disclosure is directed to one or more of the problems set forth above.